Subject: Re: sleep, usleep, and nanosleep vs. pthreads?
To: Florian Stoehr <netbsd@wolfnode.de>
From: Steven M. Bellovin <smb@cs.columbia.edu>
List: netbsd-users
Date: 09/17/2005 18:58:20
In message <Pine.NEB.4.63.0509180048230.230@mini.net.flo>, Florian Stoehr write
s:
>On Sat, 17 Sep 2005, Steven M. Bellovin wrote:
>
>> I'm trying to get gtkpod working on NetBSD. When I ran it, it went
>> into an CPU-chewing loop in the following code:
>>
>> /* keep space_ipod_free/used updated in regular intervals */
>> static gpointer th_space_thread (gpointer gp)
>> {
>> for (;;)
>> {
>> usleep (SPACE_TIMEOUT*1000);
>> if (!space_uptodate) th_space_update ();
>> }
>> }
>>
>> Contrary to the usleep call -- SPACE_TIMEOUT is 4000, so it should have
>> been a 4-second sleep -- it seemed to return either immediately or
>> virtually immediately. Changing it to use nanosleep didn't help.
>> However, using sleep() made it work.
>>
>> I'm puzzled. However, I know nothing of pthreads, so I don't know if
>> some special invocation should have been used by gtkpod to make that
>> work. The problem with usleep occurs on 2.0 and -current; the fix
>> works on -current and hasn't been tried yet on 2.0.
>>
>> --Steven M. Bellovin, http://www.cs.columbia.edu/~smb
>>
>
>>From the manpage of usleep(3):
>
The microseconds argument must be less than 1,000,000. If the value
>of microseconds is 0, then the call has no effect.
>
>It should set errno to EINVAL then.
>
Clearly pilot error on my part in not seeing that (and a worse error on
the part of the original programmer for doing it...) Any thoughts on
why nanosleep() failed? (Hmm -- maybe I should try it again, and make
sure I got it right...)
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb